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      Customized appearance 
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      <h1>
        Customized appearance
      </h1>
      <p>
        The default appearance is very usable, and indeed Logisim existed for many years with no other option. If, however, you prefer that the subcircuit be drawn differently, you can select <b class=menu>|&nbsp;Project&nbsp;|</b>→<b class=menu>|&nbsp;Edit Circuit Appearance&nbsp;|</b> , and
        Logisim's interface will switch from its regular layout-editing interface to an interface for drawing the circuit's appearance. You can also click the far-right icon (<img class="icontxt" src="../../../../img-guide/projdesign.png" alt="#########" width=16 height=16>) in the explorer pane's upper toolbar.<br> Below, we are editing the 2:1 multiplexer's appearance so that it is drawn with the usual trapezoid rather than a rectangle.
      </p>
      <p align="center">
        <img src="../../../img-guide/subcirc-5-custom-appear.png" alt="#########">
      </p>
      <p>
        With the appearance for the 2:1 multiplexer drawn as above, the layout for the 4:1 multiplexer would then appear as the following.
      </p>
      <p align="center">
        <img src="../../../img-guide/subcirc-6-custom-layout.png" alt="#########">
      </p>
      <p>
        The appearance editor is like a traditional drawing program, but there are a few special symbols for indicating how the drawing works when placed into a circuit's layout. These special symbols cannot be removed.
      </p>
      <ul>
        <li>
          <p>
            The green circle with a line coming out of it, which we'll call the <b>anchor.</b> (<img class="icontxt" src="../../../../img-guide/anchor.png" alt="#########">) There is exactly one anchor in each subcircuit appearance. Each component in a circuit has a single point identifying its
            location; a user sees this when creating a new component: The mouse click identifies just a single location, and the component is placed relative to that (usually with the primary output at the mouse's location) The anchor identifies the mouse's location relative to the overall drawing
            when the subcircuit is created.
          </p>
          <p>
            The <b>anchor</b> also identifies the appearance's facing, as indicated by the direction the anchor's line points from its circle. When placing the subcircuit into a layout, the user can change the subcircuit's facing; the anchor's facing indicates in which direction the appearance is
            oriented. In our example, the anchor is facing east, and each instance of the subcircuit in the <b class=reffig>Mux_4to1</b> is also facing east, so they are all drawn in the same orientation as the <b class=reffig>Mux_2to1</b> appearance.
          </p>
        </li>
        <li>
          <p>
            The blue circles (<img class="icontxt" src="../../../../img-guide/pinoutput.png" alt="#########">) and squares with dots (<img class="icontxt" src="../../../../img-guide/pininput.png" alt="#########">) in them are the subcircuit's <q>ports.</q> There are exactly as many ports as there are
            input and output pins in the circuit. Ports corresponding to inputs are drawn as squares, while ports corresponding to outputs are drawn as circles. Each port indicates how a wire connecting into the circuit will correspond to an input or output pin within the layout.
          </p>
        </li>
      </ul>
      <p>
        When you select a port, Logisim will indicate the corresponding pin by popping up a miniature diagram of the layout in the window's bottom right corner, with the corresponding pin(s) drawn in blue. This does not happen when all ports are selected.
      </p>
      <p align="center">
        <img src="../../../img-guide/subcirc-7-custom-layout.png" alt="#########">
      </p>
	  <p>
	    We can change the zoom of the image with a  <b class="tkeybd">Ctrl+Mouse Wheel</b> or by using the magnifying glass buttons or the slider at the bottom left of the workspace. The rate is displayed.
	  </p>
      <p>
        The toolbar contains tools for adding additional shapes, as shown below. Some keys (<b class="tkeybd">Ctrl,Alt,Shift</b>) have an effect on the way shapes are drawn. These keys can be combined with each other. 
      </p>
	   <blockquote>
        <b class="tkeybd">Ctrl</b>: Aligns the end points on the grid.<br>
        <b class="tkeybd">Shift</b>: Orient the lines at an angle multiple of 45° or make the figures symmetrical (Square, Rounded Square, Circle).<br>
        <b class="tkeybd">Alt</b>: Draws the figures from their centre. 
      </blockquote>
      <p>
        Below is a small presentation of each tool
      </p>
      <table class=toolslist>
        <tbody>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/toolselect.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Selection Tool :</strong> Select, move, copy, paste the symbols.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooltext.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Text Tool :</strong> Add, insert or edit a text.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
             <img class=inbullet src="../../../../img-guide/tooldrawline.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Line Tool :</strong> Creates a line segment.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawcurv.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Curve tool:</strong> Create a quadratic Bezier curve. The first <b class="tkeybd">click</b> and drag specifies the beginning of the line, the second <b class="tkeybd">click</b> and drag ends the line and sets the curvature. A <b class="tkeybd">click</b> on the line shows you
              the three control points. <b class="tkeybd">Shift</b> and click on central control point impose a symmetrical curve. <b class="tkeybd">Alt</b> and click on center point draws the curve through the control point (under the mouse).
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawplin.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Polylines tool</strong> Creates a sequence of connected lines, each <b class="tkeybd">click</b> starts a new line. A <b class=
              tkeybd>double-click</b> ends the sequence.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawrect.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Rectangle tool</strong> Create a rectangle or a square with rounded edges ( <b class="tkeybd">Shift</b> ) through dragging from one corner to the opposite corner.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawrrct.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Rectangle tool</strong> Create a rectangle or a square ( <b class="tkeybd">Shift</b> ) through dragging from one corner to the opposite corner.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawoval.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Oval tool</strong> Creates an oval or circle ( <b class="tkeybd">Shift</b> ) through dragging from one corner of its bounding box to the opposite corner.
            </td>
          </tr>
          <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawpoly.png" alt="#########" border="1">
            </td>
            <td>
              <strong>Polygon tool</strong> Create an arbitrary polygon, each <b class="tkeybd">click</b> starts a new face. A <b class="tkeybd">double-click</b> or <b class="tkeybd">Enter</b> key or <b class="tkeybd">click</b> the starting vertex to complete the shape.
            </td>
          </tr>
		  <tr>
            <td class=toolslist valign="top">
              <img class=inbullet src="../../../../img-guide/tooldrawdyncomp.png" alt="#########" border="1">
            </td>
			<td>
              <strong>Dynamic components</strong> Place a dynamic component <b class="tkeybd">click</b> Opens a window for the selection of components in the sub-circuits.
            </td>
		   </tr>
        </tbody>
      </table>
      <p>
        <b>Next:</b> <a href="sub-debug.html">Debugging a subcircuit</a>.
      </p>
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